--- /dev/null
+#!/bin/sh -e
+# Optimize png files in output directory
+
+find output -name "*.png" | while read png; do
+ # Reduce colors to 8bit
+ # <http://pngquant.org>
+ pngquant --skip-if-larger --force --output "$png" 256 "$png"
+
+ # Adjust bit depth, remove clutter
+ # <http://optipng.sourceforge.net>
+ optipng -o 1 -strip all "$png"
+
+ # Compress with zopfli
+ # <http://www.advancemame.it>
+ #advpng -z -4 "$png"
+done